The disclosed embodiments relate to a medical device. Specifically, the disclosed embodiments relate to a balloon catheter.
A balloon catheter expands a constricted portion formed in a blood vessel or a digestive organ to recover a flow of blood or a digestion liquid, and a fixing balloon catheter easily facilitates operation of inserted medical equipment such as a guide wire by expanding a balloon against a blood vessel wall or a digestive organ wall and fixing the balloon. Such balloon catheters mainly include a balloon that is an expansion body, an outer shaft fixed to a proximal end of the balloon, and an inner shaft inserted in the balloon and the outer shaft. Generally, the inner shaft is used to allow a guide wire to pass through the balloon catheter, and an expansion lumen provided between the outer shaft and the inner shaft is used to supply a liquid for expanding the balloon (e.g., contrast medium or physiological saline).
The conventional balloon catheter has a problematically low fixing strength between the proximal end of the balloon and the outer shaft, and the proximal end of the balloon can be removed from a distal end of the outer shaft when the balloon is expanded to expand a constricted portion or to fix the balloon to a blood vessel wall or a digestive organ wall.
As a method of solving this problem, the fixing strength between the balloon and the outer shaft can be improved by coating the outer periphery of the proximal end of the balloon and the distal end of the outer shaft with a heat shrinkable tube that is a separate member (see Japanese Patent Application Laid-open No. 2009-056297, for example). Alternatively, the fixing strength between the balloon and the distal end of the outer shaft can be improved by providing a mutually diagonally cut overlapped part between the proximal end of the balloon and the distal end of the outer shaft (see Japanese Patent No. 5237572, for example).
However, because the heat shrinkable tube is a separate member in the balloon catheter described in Japanese Patent Application Laid-open No. 2009-056297, an outer diameter of the fixing part between the balloon and the outer shaft is large, thereby causing a problem that the passing performance of the balloon catheter is deteriorated. Moreover, in the balloon catheter described in Japanese Patent No. 5237572, there is a limit to how much the fixing area between the balloon and the outer shaft can be increased, which means improvement of the fixing strength between the balloon and the outer shaft also has a limit. Especially when high pressure is imposed on the balloon, there is a risk that the proximal end of the balloon will separate from the distal end of the outer shaft.